Pump-contrclling mechanism



July 10,. 1928. 1,6? 6,81%

R. CQNRADER mi? CONTROLLING: MECHANISM Filed Jan. 17, 1924 5 sheets-sh et 1 1,678,81 R. CONRAPER IUMP CONTROLLING MECHANISM Filed Jan. 17, 1924 5 Sheets-Sheet 2 R. CONRADER PUMP CONTROLLING MECHANISM Filed Jan. 17, 1924 5 Sheets-Sheet 4 [Z v F i Z6 3 1/ E M A .37

July 10, 1928.

R. CONRADER PUMP CONTROLLING MECHANISM Filed Jan. 1'7, 19124 5 Sheets-Sheet 5 RUDOLPH CONRADER, F ERIE, PENNSYLVANIA.

rumr-oon'rnonnme MECHANISM.

Application filed January 17, 1924. Serial No. 686,771.

This invention is designed to improve the control of pumps and in carrying out the LII inlet valve.

invention I prefer to use an inlet unloader thus creating a vacuum in the pump cylinder. It is desirable where pumps of this kind are unloaded by cutting off the inlet to relieve the cylinder in addition to the unloading incident to the closing of the This has heretofore been accomplished as indicated and claimed in my application Serial Number 538,207, filed Feb. 21, 1922, patented Jan. th, 1926, #1568499. In the construction shown and claimed in said patent the relief devices are not controlled by the inlet pressure established by the unloaders. the unloaders and relief devices being controlled from a common source of pressure operating simultaneously. In the present invention 1 utilize the vacuum, or partial vacuum created at the intake with the closing of the intake unloader to control the relief valve and preferably operate the relief valve by pressure from the receiver where one cyllnder is used or the receiver and the 1ntercooler where low and high pressure c-ylinders are used, this operating pressure being controlled by a pilot valve which pilot valve is responsive to the reduction in pressure at the intake. In ns way I empty the cylinder to the receiver or the intercooler prior to opening'the'relief valve and thus not only save the amountof the fluid which is in the cylinder at the time the unloader operates but also reduce the quantity of fluid discharged through the relief valve and thus very materially reduce the pressure discharged through the reliefvalve so that the relief valve may be made of comparaair or fluid through it.

tively small size without undue velocity of In carrying forward my invention and adapting it to compound pumps I preferably make the unloader of the high pressure cylinder responsive to the same pilot valve or control which controls the, relief valve on the low pressure cylinder and operate the high pressure cylinder along the same lines as the low pressure cylinder. This method of unloading the two cylinders notonly, aocomplishes the saving of fluid in each cylinderbeforethe discharge through the relief valve but maintains in the intercooler or intermediate receptacle its full normal pressure during the unloadingv interval and also cuts off the intercooler or received so that there is no movement of fluid to and from the intercooler to either cylinder while the unloaders are operating. In carrying out my invention also I prestages, first one end and then the other, although both ends may be unloaded at. the same time if desired. Other features and details will appear from the specification and claims. 7

The invention is illustrated in the accompanying drawings as follows Fig. 1 shows a side elevation of the compressor.

Fig. 2 an end elevation.

Fig. 8 a plan view of the compressor.

Fig. 3 a modification of single-stage compressor.

Fig. 4 a side elevation of the low pressure cylinder partly in section.

Fig. 5 a central section through the high pressure cylinder.

Fig. 6 a grid for a feather valve as used on the cylinders.

Fig? 6 a plan view of the. feather plates. Fig. 6 a coverplate for the feather valve. Fig. 7 a section on the line 7-7 in Fig. 2. Fig. 8 a section on the line,88 in Fig. 7.

Fig. 9 a central section of the regulator Fig. 10.

1 marks the base of the compressor, 2 the motor driving the compressor, 3 the low pressure cylinder, 4 the high pressure cyl-' inder, 5 the inter-cooler, and 6 the intake pipe to the low pressure cylinder.

An unloader 7 is arranged in the inlet pipe, this unloader being similar to the one shown in my shown in detail in Figs. 7 and 8. It has the. inlet chamber 8, connected with the inlet pipe 6 from which two seated valve openings 9 and 10 extend, these openings being connected with the opposite ends of the cylinders. Valves 11 and 12 control the openings plungers 13 and 14:. The plungers operate in cylinders 15' and 16 and pipes 17 and 18 lead from the cylinders 15 and 16 to the regulators 19 and 20 respectively. These regulators are connected by pipes 21 and 22 with a common pipe 23 leading to a disrelief valve Patent, #1,568,499 and is 9 and 10 and are provided with so fer to unload the compressor, or pump in" charge pipe 24 leading from the high pressure cylinder or in other words from the final receiver.

The regulators may be set to work simultaneously or successively as desired. The regulator is shown in detail in Fig. 9 and is similar to the one shown and claimed in my application #678,368. It comprises the inlet fitting 25 which is connected with the receiver pressure through a pipe as 21 or 22. The fitting 25 is secured by a flanged nut 26 in a socket 28 in the body 29 of the regulator. A cylinder30 is arranged in an opening 31 in the body and has a surrounding passage 32. The cylinderis provided with inlet ports. 33 and discharge ports 34.

A piston 35 is mounted in the cylinder and operates ona push pin 36. The push pin operates on a lever 37 mounted on a pin 38. A cross head 39 is carried by an adjusting screw 40 mounted. in the lever 37 and springs 41 extend from knife-edge trunnions 42 and knife-edge trunnions 43 on the body and these springs thus resist the movement of the piston. i 4 The lever has the cams 44 and 45 which are engaged by the cam surfaces 46 and 47 on a lever 48. The lever 48 is mounted on a pin 49. A stud 50 extends from the body through an opening 51 in the lever.

spring 52 is arranged around the stud and put under tension by a nut 53 on the stud. The lever 48 operating through the cams resists the initial movement of the lever 37 and thus affords a slight variation in pressure through which the device will operate in either direction so that there will be a positive action after the device starts in either direction, the piston moving the entire distance so as to uncover the ports either to permit the air to pass in or to discharge.

When the receiver pressure reaches the desired maximum operating. on the piston, it moves the piston 'to uncoverthe inlet orts and delivers air to the unloader chamer 15 or 16 and on the plunger 13 or 14 as the case may be holding the inlet valves subject to the particular regulator. closed, thus unloading the end'of the cylinder getting its supply through the inlet valve so controlled. As soon as the inlet valve is closed the 7 pressure at the inlet side of the unloader immediately reduces as the pump continues to operate and this reduction in pressure is communicated from the inlet sides of the valves 11 and 12 through pipes 54 and 55 'respectively to relief valves 56 and 57 respectively. The relief valves and their con- -85 of the relief valves 56 and 57respectively trol are shown in detail in Figs. 10 and 11 and are similar. a The pipes 54 and 55 each lead to a cylinder 58. A plunger 59 is arranged in the cylinder and is normally 62 to the atmosphere so that the upper part of the plunger is subjected to atmospheric pressure and the lower part 'of the plunger to the pressure at the intake side of the unloader valves. As the inlet pressure is reduced, the plunger 59 is forced downwardly by atmospheric pressure and moves a stem 63 carrying a needle valve 64. The needle valve operates on a seat 65 and controls a passage 65 leading to a chamber 66. The valve 64 also operates on a seat 63 controL ling the exhaust'passage-62 leading to the opening 62 in the cylinder. The chamber 66 is mounted on an extension 67 on the top of the cap 61 and has a screw-threaded opening 68 in its upper end receiving a projec-' tion 69 on a cylinder 70. The'projcction 69 has anopening 71 forming a means of communication between the chamber 66 and the cylinder. A plunger 72 is arranged in the cylinder and the cylinder is screwed into the body 74 of the relief valve. A stem 75 is operated by the piston and a spring 76 is arranged around the stem and resists this movement. A valve 77 is arranged on the upper end of the stem and controls a pas sage 79 which is connected with the end of the pum cylinder. The valve controls the opening etween the passage and a chamber 80 and a check valve 81 is arranged in an opening 82 leading from the chamber 80 and .way of a pipe 83 as desired. The check valve has a guiding stem 84 which operates ina cap 84".

When, therefore, the pressure at the intake drops this is communicated through the cylinder 60 and with a consequent opening in the needle valve-64 on the seat 65 and closing of theneedle valve 64 on the seat 63 pressure then is delivered through the passage 65 and operates on the piston 72 thus opening the relief valve 77 and permitting the rellef of the cylinder. It will be noted that before this relief takes place the cylinder will have, of necessity, discharged such fluid as may be in the cylinder either to the intercooler or receiver thus saving the energyused as to this partially pumped fluid and at the same time reducing the pressure in the cylinder to a very slight pressure be fore a discharge takes place through the relief valve, thus reducing the work of the relief valve and making it possible to reduce the size of the relief valve and at the same sure cylinder, that is to say, between the intercooler and the cylinder, the intercooler being connected with the unloader by a pipe 89. This unloader is a duplicate of the unloader 7 on the low pressure cylinder. lipes 90 and 91 lead from the unloader 88 to relief valves 92 and 93 respectively, these relief valves being provided for the ends *1 and 1" of the high pressure cylinder. It will be noted that the unloading of the end 1 of the high pressure cylinder will follow the unloading of the end 3 of the low pressure cylinder and that the unloading of the end 4" of the high pressure cylinder will follow the unloading of the low pressure end 8" of the low pressure cylinder. The rigulators 19 and 20, as before stated, may be arranged to work insuccession'or simultaneously and the high pressure unloader and relief valve will follow in sequence.

The relief valves 92 and 93 are similar to the relief valves 56 and 57 except that the passage which leads to the pipes 86 and 87 from the relief valves 56 and 57 is closed. When, therefore, the intake pressure drops at the intake side of the unloader 88 this reduced pressure is communicated by the pipe 9091 to the pilot valve as 6-1 of the relief valve connected with the pipe and the passages 65 in the relief valves 92 and 93 are connected with the intercooler through a pipe 94 and the branch pipes 95 and 96 leading from the pipe 94 to the relief valves 92 and 93 respectively. Thus inasmuch as in this construction the intercooler is maintained at constantnormal pressure this connection is more convenient for furnishing the pressure for actuating the relief valves on the high pressure cylinderand is so utilized.

The low pressure cylinder shown in Fig. 4 is provided with inlet valves 97 and discharge valves 98. One of the advantages of this construction is the possibility of using it with the ordinary feather valves inasmuch as a separate inlet unloader is used which does not operate directly on the valve and with my construction the relief valve is controlled with this type of unloader. The compressor valves have the usual grid 99 with openings 100, the feather plates 101 operating on the grid and the feather plate 102 with the guide arches 103 and openings 10 1. These feather valves as assembled are held in place by the usual pressure yoke 105.

In these views I also show the compressor piston 3 in the low pressure cylinder and the compressor piston 4C in the high pressure cylinder. v

In the modification shown in Fig, 3 in which features of the-invention are adapted to a single stage compressor a single stage cylinder 107 is shown. This is supplied with the inlet unloader of the type of the one side unloader shown in Fig. 7 and this is controlled by a regulator 109 similar to the regulator shown in Fig. 9. The regulator is connected by a pipe 110 with a discharge pipe 111 or recelver of the pump. A pipe 112 leads from th inlet side of the unloader to a cylinder 113 corresponding in structure to the cylinder 58 (see Fig. 10) and this operates a controlling valve as 64 in a chamber 114 corresponding to the chamber 66. The chamber communicates through a pipe 115 with the receiver or discharge pipe 111 by way of a passage as 65 and this pressure is communicated through pipes 116 K leading from the chamber 114 to relief valves 117 at the ends of the cylinder so that inthis case as the inlet pressure reduces and the cylinder discharged the pilot valve is opened when the reduction is partially accomplished thus actuating the relief valves and discharging th cylinders.

lVhat I claim as new is 1. In a pump equipped with controlling mechanism, the combination of a pump cylinder; an intake unloader on the cylinder;

a relief-valve; a pilot valve responsive to intake pressure; and means controlled-by the pilot valve coi'itrolling the relief valve.

2. In a pump equipped with controlling mechanism, the combination of a pump cylinder; an intake unloader on the cylinder; a relief valve, said relief valve preventing a return flow to the cylinder; a pilot valve responsive to intake pressure; and means controlled by' the pilot valve controlling the relief valve.

3. In a pump equipped with controlling mechanism, the combination of a pump cylinder; an intake valve for the cylinder; an intake unloader on the cylinder; a relief valve;.a pilot valve responsive to pressure between the intake valve and the unloader; and means controlled by the pilot valve controlling the relief valve.

4. In a pump equipped with controlling mechanism, the combination of a pump cylinder; an intake unloader on the cylinder; a relief valve; a pilot valve responsive to'intake pressure comprising a valvev head; 1 a piston actuating the head; a controlling cylinder in which the piston operatesopen at one side to the atmosphere; a "connection leading to the controlling cylinder responsive to intake pressure; and means controlled by the pilot valve controlling the relief valve. 5. In a pump equipped with controllingv mechanism, the combination of a pump cylinder; an intake unloader on the cylinder;

a relief valve; a pilot valve responsive to intake pressure comprising a piston actuating the relief valve and a connection controlled by the pilot valve leading to a source of fluid supply; and means controlled by the pilot valve controlling the relief valve.

G. In apump equipped with controlling me hanism, the combination of a pump cylinder; an intake unloader on the cylinder; a relief valve; a pilot valve responsive to intake pressure comprising a piston actuating the relief valve and a connection controlled by the pilot valve leading to a source of fluid supply; means controlled by the )ilot valve controlling the relief valve and a check valve preventing a return flow through the relief valve.

7. In a pump equipped with controlling mechanism, the combination of two cylinunloader for the high pressure cylinder; and

means responsive to the 'unloaded pressure condition of oneof the cylinders and independent of intercooler pressure controlling the unloader of the other cylinder.

9. In a'pump equipped-with controlling mechanism, the combination of two cylinders; unloaders for said cylinders, one of said unloaders operating on the intake of its cylinders; an intcrcooler between said cylinders; and means responsive to the unloaded pressure condition of the cylinder having the unloader operating on its intake and independent of intercooler pressure actuating the unloader of the other cylinder.

10. In a pump equipped with controlling mechanism, the combination of a low pressure cylinder; an intercooler; a high pressure cylinder to which the low pressure cylinder discharges and discharging to the high pressure cylinder; an unloader operating on the intake of the low pressure cylinder; an unloader for the high pressure cylinder; and means responsive to the unloaded pressure ondition of the low pressure cylinder and independent of intercooler pressure controlling the unloader of the high pressure cylinders l 11. Ina pump equipped with controlling mechanism, the combination of two cylinders;

unloaders for said cylinders; and a p1lot-valve controlling the unloader of .one cylinder, said pilot valve being responsive to unloaded conditions of the othercylin'der.

12. Ina pump equipped with controlling mechanism, the-combination of two cylinders; unloaders for said cylinders, one of said unloaders operating on the intake of its cylinder; and a pilot valve responsive to unloaded conditions of the cylinder controlled by the intake unloader controlling the unloader of the other cylinder.

13. In a pump equipped with controlling mechanism, the combination of a lOW pressure cylinder; a high pressure cylinder to which the low pressure cylinder discharges; an intake unloader for the low pressure cylinder; an unloader for the high pressure cylinder; and a pilot valve responsive to in take conditions of the low pressure cylinder controlling the unloader of the high pressure cylinder.

14.. Ina pump equipped with controlling mechanism, the combination of two cylinders; unloaders for said cylinders; a relief valve for one cylinder; and means responsive to unloaded conditions of the cylinder having the relief valve operating the relief valve and unloader of'the other cylinder.

15. Ina pump equipped with controlling mechanism, the combination of a 10W pressure cylinder; a high pressure cylinder; arelief valve for one of said cylinders; un-

loaders for said cylinders; and means responsive to the unloaded condition of the cylinder having the relief valve operating the relief valve and unloader-of the other cylinder.

16. In a pump equipped with controlling mechanism, the combination of a low pressure cylinder; a high pressure cylinder; unloaders for said cylinders; a relief valve for the low pressure cylinder; and means responsive to the unloaded condition of the low pressure cylinder operating the relief valve and the unloader of the high pressure cylinder.

17. In a pump equipped with controlling mechanism, the combination of a low pressure cylinder; a high pressure cylinder; an intake unloader for the low pressure cylinder; an unloader for the high pressure cylinder; a relief valve for the low pressure cylinder; and means responsive to the intake pressure of the low pressure cylinder controlling the relief valve and the unloader of the high pressure cylinder.

18. In a pump equipped with controlling 'mechanism, the combination of a low pressure cylinder; a high pressure cylinder to which the lOW pressure cylinder discharges; unloaders for said cylinders; and relief valves for said cylinders, each relief valve being responsive to .unloaded conditions of its cylinder.

19. In a pump equipped with controlling mechanism, the combination of a low pressure cylinder; a high pressure cylinder to which the low pressure cylinder'discharges; intake unloader-s for said cylinders; and

relief valves for said cylinders, each relief valve being responsive to intake pressures of its cylinder.

20. In a pump equipped with controlling mechanism, the combination of two cylinders; unloaders-for said cylinders; a relief valve for one cylinder; and means responsive to unloaded conditions of the cylinder having the relief valve operating the relief valve and unloader of the other cylinder comprising a pilot valve responsive to unloaded conditions of the cylinder having the relief valve and controlling a fluid actuating the relief valve.

21. In a pump equipped with controlling mechanism, the combination of a low pres sure cylinder; a high pressure cylinder; unloaders for said cylinders; a relief valve for each of said cylinders; and a pilot valve responsive to the unloaded condition of one of the cylinders having the relief valve and controlling the relief valve and the unloader of the other of said cylinders.

22. In a pump equipped with controlling mechanism, the combination of two cylinders; unloaders for said cylinders, one of which operates on the inlet of the cylinder; a relief valve for the cylmder having the inlct unloader; and means responsive to the unloaded condition of the cylinder having the inlet unloader operating the relief valve and the unloader of the other cylinder.

23. In a pump equipped with controlling mechanism, the combination of a low pressure cylinder; a high pressure cylinder; an inlet unloader for the low pressure cylinder; a relief valve for the low pressure cylinder; and means responsive to the inlet pressures of the low pressure cylinder controlling the relief valve and the unloader of the high pressure cylinder.

24. In a pump equipped with controlling mechanism, the combinationof a low pressure cylinder; a high pressure cylinder; an inlet unloader for the low pressure cylinder; a relief valve for the low pressure cylinder; means responsive to the inlet pressures of the low pressure cylinder controlling the relief valve and the unloader of the high ressure cylinder; and a relief valve for the high pressure cylinder responsive to unloaded conditions of the high pressure cylinder.

25. In a pump equipped with controlling mechanism, the combination of a low pressure cylinder; a high pressure cylinder, to which the low pressure cylinder discharges;

inlet unloaders for said cylinders; relief valves for sald cylinders; means controlled by the unloaded condition of the low pressure cylinder controlling the relief valve of the low pressure cylinder and the unloader of the high pressure cylinder; and means responsive to the unloaded condition of the high pressure cylinder controlling the relief valve of the high pressure cylinder.

26. In a pump equipped with controlling mechanism, the combination of a pump having a low pressure cylinder and a high pressure cylinder; a receptacle between the cylinders receiving the discharge from the low pressure cylinder and discharging to the high pressure cylinder; and an unloading mechanism for said cylinders maintaining the receptacle pressure normal during the period the unloading mechanism is acting, the unloader of one of the cylinders being responsive to the unloaded condition of the other of said cylinders.

27. In a pump equipped with controlling mechanism, the combination of apump having a low pressure cylinder and a high pressure cylinder; a receptacle between the cylinders receiving the discharge from the low pressure cylinder and discharging to the high pressure cylinder; and an unloading mechanism for said cylinders maintaining the receptacle pressure normal during the period the unloading mechanism is acting, the unloader of the high pressure cylinder being responsive to the unloaded condition of the low pressure cylinder.

28. In a pump equipped with controllingmechanism, the combination of a pump having a low pressnrecylinder and a high pressure cylinder; a receptacle between the cylinders receiving the discharge from the lp w pressure cylinder and discharging to the high pressure cylinder; and an unloading mechanism for said cylinders maintaining the receptacle pressure normal during the period the unloading mechanism is acting,

comprising a pilot valve responsive to unloaded conditions in one of the cylinders and .controling the unloader of the other cylinder.

29. In a pump equipped with controlling mechanism, the combination of a pump having a low pressure cylinder and a high pressure cylinder; a receptacle between the cylinders receiving the-discharge from the low pressure cylinder and discharging to the high pressure cylinder; and an unloading mechanism for said cylinders maintaining the receptacle pressure normal during the peinders receiving the discharge from the low pressure cylinder and discharging to the high pressure cylinder; and an unloading mechanism for said cylinders maintainifig the receptacle pressure normal during the period the unloading mechanism is acting, comprising a pilot ,valveresponsive to the unloaded conditions of the low pressure cylinder and controlling the unloader of the high pressure cylinden. 1

31. In a pump equipped with controlling mechanism, the combination of a pump havlow pressure cylin ing a low pressure cylinder and a high pressure cylinder; a receptacle between the cylinders receiving the discharge from the low pressure cylinder and discharging to the high pressure cylinder; an unloading mechanism for said cylinders maintaining the receptacle pressure normal during the period the unloading mechanism is acting; a relief valve for one of the cylinders; and means responsive to the unloaded condition of the cylinder having the relief valve actuating the relief valve. 1

32. In a pump equipped with controlling mechanism, the combination of a pump having a low pressure cylinder and a high pressure cylinder; a receptacle between the cylinders receiving the discharge from the low pressure cylinder and discharging to the high pressure cylinder; an unloading mechanism for said cylinders maintaining the receptacle pressure normal durin the period the unloading mechanism is acting; a relief .valve for the low pressure cylinder; and

means responsive to unloaded conditions of the low pressure cylinder controlling the relief valve.

33. In a pump equipped with controlling mechanism, the combination of a pump having a low pressure cylinder and a high pressure cylinder; a receptacle between the cylinders receiving the dischargefrom the mechanism, the combination of. a pump havlow pressure cylinder and discharging to the high pressure cylinder; an unloading mechanism for said cylinders maintaining the receptacle pressure normal during the e unloading mechanism is acting;

period t a relief valve for the low pressure cylinder; and means responsive to unloaded conditions of the low pressure cylinder controlling the relief valve and the unloader of .the high pressure cylinder.

34.- In a pump equipped with controlling mechanism, the combination of a pump having a low pressure cylinder and a high pressure cylinder; a receptacle between the cylinders receiving the discharge from the low pressure cylinder and discharging to the high pressure cylinder; and an unloading mechanism for said cylinders maintaining the receptacle pressure normal during the period the unloading mechanism is acting; the unloading mechaniln of the low pressure cylinder operating on the intake of said cyl- Jinder and the unloader of the high pressure.

cylinder acting in response to unloaded conditions of the low pressure cylinder.

35. In a pump equipped'with controlling mechanism, the combination of a pump having a low pressure cylinder and a high pressure cylinder; a receptacle between the cylinders receivin the discharge from'the der and discharging to the high pressure cylinder; an unloading mechamsm for said cylinders maintaining the receptacle pressure normal during the period the unloading mechanism is acting, the unloader of the low pressure cylinder operating on the intake of the low pressure cylinder; a relief valve for the low pressure cylinder; and means responsive to the intake pressure of the low pressure cylinder actuating the relief valveand the unloader of the high pressure cylinder.

36.-In a pump equippedwith controlling mechanism, the combination of a pump having a lowpressure cylinder and a high pressure cylinder; a receptacle between the cylinders receiving the discharge from the loW- pressure cylinder and discharging to the high pressure cylinder; an unloading mechanism for said cylinders maintaining the receptacle pressure normal during the period the unloading mechanism is acting, the unloader of the low pressure cylinder operating on the intake of the low pressure cylinder; a relief valve for the low pressure cylinder; means responsive to the intake pressure of the low pressure cylinder actuating the relief valve and the unloader of the high pressure cylinder; a relief valve for the high pressure cylinder; and means responsive to the unloaded conditions-of the high pressure cylinder actuating the relief valve of the high pressure cylinder.

37. In a pump equipped with controlling high pressure cylinder; an unloading mechanism for said cylinders maintaining the receptacle pressure normal during the period the unloading mechanism is acting; relief valves for said cylinders; means responsive to the intake pressure of the low pressure cylinder controlling the low pressure cylinder relief valve and the unloader ofthe high pressure cylinder; and means responsive to the intake pressure of the high pressure cylinder controlling the relief valve of the high pressure cylinder.

38. In a pump equipped with controlling mechanism, the combination of a pump cylinder; an intake unloader on the cylinder; a relief valve; a pilot valve responsive to intake pressure comprising a piston actuating the relief valve; a connection controlled by the pilot valve leadingto a source of fluid supply; an exhaust passage, the connection and exhaust passage being alternately opened by the pilot valve; and means controlled by the pilot valve controlling the relief valve.

In testimony whereof I have hereunto set my hand. 

